SQL Server枢轴/取消枢纽

Question

我正在尝试找到一种方法来转换我将表中所有列排序为行的表

EmpID       Day             StartTime
-------------------------------------------------
  4       SUNDAY           10:00:00 AM
  4       MONDAY            8:00:00 AM
  4       TUESDAY           8:00:00 AM
  4       WEDNESDAY         8:00:00 AM
  4       THURSDAY          8:00:00 AM
  4       FRIDAY            NULL
  4       SATURDAY          NULL
 800      SUNDAY           10:00:00 AM
 800      MONDAY            8:00:00 AM
 800      TUESDAY           8:00:00 AM
 800      WEDNESDAY         8:00:00 AM
 800      THURSDAY          8:00:00 AM
 800      FRIDAY            NULL
 800      SATURDAY          NULL

INTO

EmpID       Sunday(Start Time)      Monday(Start Time)         
-------------------------------------------------
  4          10:00:00 AM             8:00:00 AM

等...

我已经看到了Pivot和Unpivot的示例，但是对于Pivot / Unpivot函数，这会很复杂吗？

Answer 1

如果您想使用PIVOT

示例

 Select *
  From  YourTable src
  Pivot ( max(StartTime) for Day in ([Sunday],[Monday],[Tuesday] )  ) pvt

注：假定YourTable是示例中显示的3列。如果您有多余的列，则YourTable应替换为子查询，例如

From (Select EmpID,Day,StartTime From YourTable) src

Answer 2

我只使用条件聚合：

select empid,
       max(case when day = 'Sunday' then StartTime end) as Sunday_StartTime,
       max(case when day = 'Monday' then StartTime end) as Monday_StartTime,
       . . .
from t
group by empid;